Cliff swallows of a feather
By Cristin Ross
Athens Review Online
If you’ve driven under the bridges of Loop 7 in Athens on any given morning lately, you may have noticed flurries of winged activity along the sides of those bridges.
That would be your typical cliff swallow, making the most of a morning meal — mostly likely mosquitoes.
Like its close relative the Barn Swallow (Hirundo rustica), the cliff swallow (Petrochelidon pyrrhonota) has benefited from the proliferation of manmade nesting sites, reports the Cornell Laboratory of Ornithology. Once restricted to nesting on the cliff faces of the west, cliff swallows, which eat only insects, now most often nest under bridges, culverts, and under the eaves of buildings.
“These birds are fairly common in East Texas,” said Texas Parks and Wildlife biologist David Sierra. “I think highway bridges are the equivalent of blue bird nest boxes for a cliff swallow, and the greater numbers of these bridges and other structures they can use are helping their populations grow. That’s good for us, since they eat a huge amount of those flying insects that tend to bug us.
“They are very agile flyers, so they seem able to adapt to traffic well, so traffic under a bridge poses a minimal threat to them.”
According to the Cornell Web site, www.birds.cornell.edu, the bird was first noted breeding in New York in 1817 and became widespread by the beginning of the 20th century. Declines followed the introduction and spread of the House Sparrow, a species that may dispossess cliff swallows by taking their nests and destroying any eggs already laid. The modern practice of painting wooden barns and of using metal or other smooth materials has also apparently inhibited cliff swallow nesting, but the use of bridge and dam sites for their nests seems to be increasing.
“It takes a long time to build a nest,” Sierra said. “And most nesting pairs will come back to a nest year after year, so don’t knock them down, thinking they aren’t of any use anymore.”
Cliff swallows build gourd-shaped nests out of mud pellets that they carry in their mouths to a nest site protected by an overhang. The typical nest contains approximately 1,000 mud pellets when finished, and is lined with grasses and feathers.
“Their spit is kind of sticky and that helps to form the pellets and adhere them to the rest of the nest and to the side of the bridge,” Sierra said.
Usually a nest is grayish in color, but the nests of those birds in Athens are the distinctive red-orange color indicative of East Texas red clay.
Nests, begun as a shelf adhered to a vertical surface, are located in colonies averaging a few hundred nests and ranging up to two or three thousand in the west.
A colony serves as an “information center” for feeding birds, as unsuccessful foragers may follow successful birds to food sources. Both sexes share in incubating and feeding chicks.
The species is migratory and spends the winter in more tropical climates, including South America.
Cliff swallows have glossy blue-black backs streaked with white and a cinnamon rump. The wings and square tail are brownish black. Underparts are white with the upper breast sides and flanks pale gray brown. The throat and sides of the head are chestnut. Below the throat is a patch of black at the top of the breast. The forehead is white to pale brown. Both sexes look alike.
In the United States, all swallows are classified as migratory insectivorous birds under the Migratory Bird Treaty Act of 1918, as found at the Web site www.ces.ncsu.edu. Swallows are also protected by state regulations. It is illegal for any person to take, possess, transport, sell, or purchase swallows or their parts, such as feathers, nests, or eggs, without a permit. As a result, certain activities affecting swallows are subject to legal restrictions.
Add comment June 13th, 2006